Integer attribute values being cast to decimal in some very specific cases

[digitalpianism]

Everything you need to know is listed under this Magento Stack Exchange question: http://magento.stackexchange.com/questions/105244/magento-1-admin-product-grid-column-value-disappear-on-name-search/105421

Even though the question I asked was about Magento 1, it seems like this bug is still present in Magento 2 and I'm about to make a PR to fix it.

[digitalpianism]

Quick side note on how to quickly replicate the issue on Magento 2:

This is a quick dirty script I've created in order to show the problem on M2:

Create the following file: /dev/tests/unit/test.php:

<?php
require "../../../app/bootstrap.php";
class Test extends \PHPUnit_Framework_TestCase
{
    public function testExample()
    {
        $bootstrap = \Magento\Framework\App\Bootstrap::create(BP, $_SERVER);

        $obj = $bootstrap->getObjectManager();

        $prod = $obj->create('\Magento\Catalog\Model\ProductFactory');

        $col = $prod->create()->getCollection()->addAttributeToSelect('tax_class_id')->addAttributeToSort('name')->addAttributeToSelect('price')->setPageSize(1);

        var_dump($col->getFirstItem()->getData('tax_class_id'));

        $col = $prod->create()->getCollection()->addAttributeToSelect('tax_class_id')->addAttributeToSort('name')->setPageSize(1);

        var_dump($col->getFirstItem()->getData('tax_class_id'));

    }
}

When you run phpunit test.php from the dev/tests/unit folder, you will get the following result:

string(1) "2"
string(6) "2.0000"

As you can see, without the addAttributeToSelect('price') call, the result is what we expect, the value of the tax_class_id attribute as it is supposed to be: an integer.

However, when you add the addAttributeToSelect('price'), the result differs and we get a tax_class_id value casted as a decimal.

[piotrekkaminski]

Closing in favor of PR #3705